The mechanism of Arhalofenate in alleviating hyperuricemia?Activating PPARγ thereby reducing caspase-1 activity

Hyperuricemia (HUA) is an important risk factor for renal diseases and contributes to gout. Arhalofenate (Arha) has been proved to have uricosuric activity as an inhibitor of URAT1, organic anion transporter 4 (OAT4) and OAT10. However, the effects of Arha on HUA remain unknown. The objective of this study was to investigate whether Arha could alleviate HUA and uncovered the underlying mechanism in vitro. HK-2 cells were exposed to uric acid (UA) to simulate HUA in vitro. Then cells were treated with Arha, caspase-1 inhibitor Belnacasan (Beln), caspase-11 inhibitor Wedelolactone (Wede) and PPAR gamma inhibitor Mifobate, respectively. The alteration of cell proliferation, inflammation, pyroptosis and expression of related proteins were detected. Results showed that UA exposure inhibited cell viability and increased IL-1 beta and IL-18 generation in a concentration dependent manner. Meanwhile, UA activated the cleavage of gasdermin D (GSDMD), enhanced the protein expression of URAT1, OAT4, TLR4, caspase-1, and caspase-11 and reduced PPAR gamma expression. While the presence of Arha or Beln enhanced cell viability and inhibited cleavage of GSDMD. Wede slightly increased cell viability but failed to prevent GSDMD cleavage. The expression of related proteins except caspase-11was also recovered by Arha. Beln and Wede partially rescued related proteins level except PPAR gamma compared with model group. Besides, the co-treatment of Mifobate blunted the effects of Arha on cell viability and expression of GSDMD, TLR4, and caspase-1. In conclusion, Arha inhibited UA transport as well as preventing inflammation and pyroptosis via activating PPAR gamma thereby blocking caspase-1 activation of HUA in vitro.